In the United States and many other countries, heart disease is a leading cause of death and disability. One particular kind of heart disease is atherosclerosis, which involves the degeneration of the walls and lumen of the arteries throughout the body. Scientific studies have demonstrated the thickening of an arterial wall and eventual encroachment of the tissue into the lumen as fatty material builds upon the vessel walls. The fatty material is known as “plaque.” As the plaque builds up and the lumen narrows, blood flow is restricted. If the artery narrows too much, or if a blood clot forms at an injured plaque site (lesion), flow is severely reduced, or cut off and consequently the muscle that it supports may be injured or die due to a lack of oxygen. Atherosclerosis can occur throughout the human body, but it is most life threatening when it involves the coronary arteries which supply oxygen to the heart. If blood flow to the heart is significantly reduced or cut off, a myocardial infarction or “heart attack” often occurs. If not treated in sufficient time, a heart attack often leads to death. Further, the weakening of vessel walls can lead to an aneurysm or swelling of the vessel that, if left untreated, will rupture and lead to internal bleeding and often death. Aneurysms commonly occur in the aorta.
The medical profession relies upon a wide variety of tools to treat heart conditions and major vessel diseases, ranging from drugs to minimally invasive procedures to open heart “bypass” surgery. Often, a lesion can be diagnosed and treated with minimal intervention through the use of catheter-based tools that are threaded into the coronary arteries via the femoral artery in the groin. For example, one treatment for lesions is a procedure known as percutaneous transluminal coronary angioplasty (PTCA) whereby a catheter with an expandable balloon at its tip is threaded into the lesion and inflated. The underlying lesion is re-shaped, and hopefully, the lumen diameter is increased to improve blood flow. In the case of aortic aneurysms, an endovascular aortic repair (EVAR) or thoracic endovascular aortic repair (TEVAR) may be utilized to introduce a stent graft into the vasculature. Such techniques have traditionally relied on CT scans performed before surgery and angiograms during surgery to identify important anatomical features of the vasculature associated with the interventions. However, the information from a CT scan is often inaccurate at the time of surgery since the aneurysm or other condition is continually evolving over time.
In recent years, a technique has been developed for obtaining detailed information about coronary and peripheral vessels. The technique, known as Intravascular Ultrasound (IVUS), employs one or more very small transducers arranged towards the end of a catheter to provide electronically transduced echo signals to an external imaging system in order to produce a two or three-dimensional image of the lumen, the vessel tissue, and/or the tissue surrounding the vessel. These high quality images are generated in substantially real time. The IVUS images allow a user to view the form and structure of a site within a vessel rather then merely determining that blood is flowing through a vessel.
While the existing devices and methods have been generally adequate for their intended purposes, they have not been entirely satisfactory in all respects. The imaging catheters, systems, and associated methods of the present disclosure overcome one or more of the shortcomings of the prior art.